public class Demo07 {
    public static void main(String[] args) {
        Thread t=new Thread(()->{
            System.out.println("线程7");
        });
        t.start();

        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }
        System.out.println(t.isAlive());
    }
}
